Testing of unreinforced masonry walls seismically retrofitted with ECC shotcrete

Abstract

Engineered Cementitious Composite (ECC) is a type of strain-hardening cement composite that was sprayed onto unreinforced masonry (URM) walls in order to determine the suitability of using this method of application as a seismic retrofitting technique for URM buildings. From studies considering the mix design of ECC it was determined that sand is a crucial component influencing the strain-hardening behaviour. Following improvement of the sand used, an ECC with an ultimate tensile strain capacity of 2% was obtained and three brick high prism samples with ECC sprayed onto one face were tested in axial compression and found to exhibit five times the energy absorption of the non-retrofitted prisms when using 10 mm of ECC reinforcement. Retrofitted masonry wallettes were tested to determine their diagonal in-plane response and results showed that ECC had successfully modified the brittle behaviour of non-retrofitted samples, to instead exhibit ductile behaviour. Finally, two 4.1 m high walls were constructed to test out-of-plane response. It was determined that 30 mm of ECC was able to increase the out-of-plane load capacity of the wall by a factor of 13.2 when sprayed on the tension surface and increased the load capacity of the wall by a factor of 1.6 when applied on the compression surface. It is concluded that ECC is an effective material for both in-plane and out-of-plane seismic retrofitting of URM buildings